Electrical testing



March 7, 1933. E, WQODBURY 1,900,424

ELECTRICAL TESTING Filed Sept. 27, 1927 Patented Mar. 7, 1933 UNITED STATES EUGENE WOODBURY, or LINCOLN PARK, NEW JERSEY ELECTRICAL TESTING This invention relates to testing and particularly to testing conductors in electrical systems for continuity and where a number of conductors are grouped together for identity.

A broad object of the invention is to provide a quick and labor saving method of identifying electrical conductors at one or more points along their lengths.

A specific object of the invention is to provide a simple, compact, and low priced apparatus for use withthe above method of testmg. A It is common practice to conceal electrl- 1 5 cal conductors by grouping a largenumber of them together in a cable, or by enclosing several conductors in a conduit. Since such conductors must often be identified at vari-' ous points along their lengths in order to properly connect them to apparatus, or to other conductors, it has been a common practice in the past to cover different conductors with differently colored or marked insulation. This makes them readily identifiable, but in a great many cases it is not practicable to use insulation of different colors and in such cases it is necessary toidentify the conductors by electrical tests, which are usually carried out as follows: Two testmen are 10- V cated at the two terminals respectively of the conductor to be identified, one of whom con- Application filed September 27, 1927. Serial No. 222,380,

tors at once with alternating or pulsating currents of distinctly different frequencies so that they may be readily distinguished apart.

My improved apparatus for, and method of, testing will now be described and explained in connection with the drawing, which shows schematically a conduit containing conductors to be identified at a plurality of points, a device in accordance with my invention, and the method of using it.

vReferring to the drawingI have shown a plurality of buzzers8, 9, 10 and 11 of conventional type, each comprising an electromagnet with a vibratory armature and aback contact for closing the electromagnet ener gizing circuit when the armature is in its normal position of rest. The back contacts of all the buzzers are connected to one terminal of the battery 12 and the other terminal of battery 12 is connectedto binding post 7. One end of the winding on each buzzer is connected to its respective armature and the other end to one of the binding posts 4. The assembled buzzers and battery may conveniently be placed in a compact: container with the binding posts 4 and 7 mounted on the exterior thereof.-

The circuit for the operation of any buzzer may betraced from battery 12, through the back contact, armature and winding of the buzzerto one of the binding posts 4, and it is necessary to complete the circuit between the latter binding post and bindingpost 7, which is connected to the other pole of battery'12, in order to operate the buzzer. When this circuit is closed the buzzer will vibrate its armature at a speed, or frequency, dependent largely on the inertia of the armature and the stiffness of the armature support.v In accordance with this principle of vibrating bodies the armatures of the four buzzers 8, 9,10 and 11 are so proportioned as to vibrate at different frequencies." Thus buzzer 8 has a massive armature mounted on a flexible support so that it vibrates at a very low frequency, whereas buzzer 11 has a very light armature mounted on a relatively stiff support so that it vibrates at a much higher frequency than does buzzer 8. Buzzers 9 and 10 have their armatures and armature supports so proportioned that they vibrate at different frequencies, which may be higher than that of buzzer 8 but lower than that of buzzer l1. a v

To illustrate the method of utilizing the above described apparatus a conduit 5' containing a plurality of conductorsrl which are tobe identified at a plurality of points along their length, is shown in the drawing.

This conduit may, for instance, run vertically in a building and have an outlet for the con-' nection of apparatus on each floor. F urthermore it is assumed that the electrical circuit involved is of such anature that each conductor must be connected to adefinite terminal of the apparatus at each outlet.

In accordance with this invention the conductors 1 maybe speedily tested and identified as follows: 1

The apparatus comprising the buzzersand battery, shown enclosed in the dotted line,

is placed at the terminal of the conduit and the conductorsl connected to difierent buz zers at binding posts 4, and the binding post 7 is connected to the metal conduit, as shown in the drawing. "With the connectionsmade V as shown, if any one of the conductors is grounded on the conduit, as the result of faulty insulation, a circuit will be closed from battery 12 to the conduit (through binding post 7) through the fault in the insulation to the conductor and its associated buzzer,

which immediately buzzes to inform the test man that the conductor is grounded in the If the buzzers remain quiet the conduit testman knows at once that'the insulation on the conductors is good and that he can pro;

ceed to test them for continuity and identity.

' To do this he firstv notes theorder in which the'conductors are connected to the'buzzers.

For instance if there are three conductors he may connect :number one conductor to the lowest frequency buzzer, number two conductor to a higher frequencybuzzer andnumher three conductor toa still higher frequency buzzer.

V to the different remotepoints at which the I ,oer-one, numbertwo or number three con,-

' ductor. If no sound is heard the testman knows that r the I conductor is broken or open The testman then proceeds that as the result of performing a single operation he is apprised as to the identity and continuity of one of a group of conductors. What is claimed is:

1. Theinethod of identifying a plurality 'of electrical conductors at different points.

along their length which comprises applying.

acurrent which varies in'magnitude at a definite time rate to one conductor andapplying currents which vary at different time rates'tothe other conductors and causing said currents to produce different, distinctive indications at said different points along their length, whereby theymaybe identified.

" 2, The method ofidentifying a plurality of conductors at a remote point which comprises applying to each conductor a current which variesinmagnitude at a time rate different from that ofthe current applied to each other conductor and causing-said difier- 'ent currents to produce different, audible indications at the remote point.

a The method of identifying electrical conductors which comprises applying pulsatin'g electric currents of difierenndistinctive frequencies to dili'crentconductors and identifying each conductor wherever'itmay ap- I pearby determining tliefrequency of the current impressed thereon. I

. {L A portable test set for testing a plural ity ofcircuits comprising a source 'ofelectric current and a pluralityof contacts adapted to vibrate at diiierent frequencies a common terminal for connection to all circuits to be tested, and a plurality of terminals for connection individually todifferent circuits to be tested, each contact adapted'to open'and close,

with each vibration, a series circuit lnclucling the source of electric current, said common.

terminal, ando'neof saidpluralityof ternii nals individual to'ieach vibrating contact. 5; A portable test-setcomprising an electric battery, a pluralityof terminals on the exterior of said" set for connection to circuits to be tested, a plurality of buzzers, each comprising an electrom'agnet and an armature,

a back contact against which said armature normally rests, .said' electromagnet, 'ariua- 'ture' and'contact of each'buzzer being connected in seriesand 'each buzzer being connected between a'separate one of said terminals onthe exter or of said set and one pole of the battery, theother pole of said battery be- ,ing connected to another of said terminal 0 the exterior of said set) 6. The method of testing a. plurality of normally open'circuits whichcomprises conditioning said circuits whereby a distinctive E. F, will be applied'to each circuit only upon closure of that circuit. 7

7. A portable test set comprising a plural ity of circuits each including a normally inactive" ClICllll? interrupting device adapted upon closure of its associated circuit to in-.

terrupt the circuit at a predetermined audible rate and at the same time to emit a distinctive sound, each circuit including in series therewith, a pair of normally open circuit terminals fol-connection to a circuit to be tested whereby said interrupting device is operated only when a circuit is closed between said terminals.

In witness whereof, I hereunto subscribe my name this 20 day of September A. D.

EUGENE WOODBURY. 

